Fingerprint of GeV scale right-handed neutrinos on inflationary gravitational waves and PTA data

Understand

We show that the seesaw mechanisms that exhibit right-handed neutrino mass-dependent non-standard post-inflationary cosmology make blue-tilted inflationary gravitational waves (GW) compatible with the recent findings of nHz stochastic GW background by the pulsar-timing arrays (PTAs) for high reheating temperatures.

• The right-handed neutrino (RHN) mass scale has to be $\mathcal{O}(\rm GeV)$.
• Remarkably, such a scenario produces a correlated signature testable by the future LIGO run.
• In addition to contributing to the active neutrino masses, $\mathcal{O}(\rm GeV)$ RHNs generate baryon asymmetry of the universe via low-scale-leptogenesis.